1. Field of the Invention
This invention relates generally to new and useful chemical compounds, and more particularly to cross-linkable polymers generated using the Mannich reaction.
2. Description of the Related Art
The Mannich reaction provides a synthetic route to production of amine derivatives from materials containing active hydrogen atoms. An amine compound (i.e., ammonia or a primary or secondary amine) is reacted under mild acid or alkaline conditions with formaldehyde and a compound (often a ketone) that contains at least one active hydrogen atom to form the substituted amine derivative, with the active hydrogen atom replaced by a methylene group (derived from formaldehyde) which is also bound to the nitrogen atom.
The Mannich reaction has also been used to generate oligomers and polymers by combining two moles of formaldehyde for every mole of active-hydrogen compound and ammonia or primary amine. See, e.g., Tsuchida & Hasegawa, 14 Polym. Lett. Edn. 103 (1976). Mannich oligomers and polymers of this type are primarily (if not completely) linear, and do not provide molecular sites where cross-linking can take place. Their industrial application, accordingly, is limited. Other examples of linear Mannich polymers appear in U.S. Pat. Nos. 4,231,759; 4,396,517; 4,561,901; 4,912,247; and 5,016,495.
At the same time, traditional cross-linked polymers suffer from disadvantages as well. Typically, these are provided in the form of uncured prepolymer resins which, when exposed to a suitable triggering mechanism (e.g., heat, particular pH levels, or an additional reaction component) undergo the cross-linking reaction. The resins (as well as any necessary solvents) are ordinarily liquid. Liquids can be inconvenient to transport, imposing significant added costs of usage. Resins (and/or solvents used in conjunction therewith) may also exude foul or even toxic odors, necessitating further inconvenience and expense to maintain environmental quality. And of course the polymer itself can be costly if expensive functionalities (such as epoxy or isocyanate) are utilized.
Cross-linking polymer systems also tend to be limited in terms of versatility, since it is ordinarily difficult to vary polymer compositions sufficiently to obtain a range of rheological or other physical properties.